XML Diagrams

An XML diagram provides a graphical view of the elements that comprise an XML schema definition in a tree format.

Note: To create an XML diagram in an existing XSM, right-click the model in the Browser and select New > XML Model Diagram. To create a new model, select File > New Model, choose XML Model as the model type and XML Model Diagram as the first diagram, and then click OK.

The following example shows the diagram of an XSM which models an XML schema for Resume documents:

Right-click a symbol in an XML diagram and select one of these features:

Expand - to expand the first level of the hierarchy below the symbol.
Expand All - to expand the whole hierarchy below the symbol.
Collapse - to hide the hierarchy below the symbol.
Arrange Symbols- to reorganize the hierarchy below the symbol.

Note: The Symbol > Group Symbols command only acts on free symbols in an XML diagram.

If an XML model is too large or too complex, you can create several diagrams to have partial views of the model and focus on certain objects.

For example, the original Resume diagram could be split into five diagrams, corresponding to the five main objects of the model (Main, Contact, Achievement, Description and Address).

The following illustration shows the Achievement sub-diagram:

XML Diagram Objects
An XML model represents the structure of a potential or existing XSD, DTD, or XDR through a tree structure of elements. PowerDesigner supports all the objects necessary to build XML diagrams.
Elements (XSM)
Elements are the basic building blocks of an XML model, which organizes them into a tree structure. Elements can contain other elements (via group particles) and attributes, and can reference groups, attribute groups and simple and complex types.
Attributes (XSM)
Attributes can be created under elements or complex types or directly at the root or in an attribute group for reuse.
Group Particles (XSM)
An element composed of other elements is a parent element with child elements.
Simple Types (XSM)
A simple type is a data type definition defined by derivation of an existing simple type (built-in data type or derived simple type). It can be used by elements or attributes with text-only content; it cannot contain elements or attributes. You can only create simple types in a model targeting XSD.
Complex Types (XSM)
A complex type is an element that contains other elements or attributes, and which is used to define a data type to be reused and derived by extension or restriction.You can only create complex types in a model targeted with XSD.
Groups (XSM)
A group of elements is a set of elements arranged by a group particle (all, choice or sequence), which is then referenced in the model by various elements.
Attribute Groups (XSM)
An attribute group is a set of attributes, which is referenced in the model by various elements. It is created independently, without a parent element, and can be reused multiple times by elements, complex types or other global attribute groups, through references. In a schema, it is directly linked to the <schema> tag (root element). Attribute groups are not supported by XDR.
Any Elements (XSM)
Any elements allow you to attach any type of object to a choice or a sequence group particle.
Constraints: Keys, Uniques, and KeyRefs (XSM)
Constraints indicate that element values must be unique within their specified scope. In a schema, a constraint is declared with the <unique>, <key>, or <keyRef> tag. Constraints are only available in a model targeted with XSD.
Derivations: Extensions, Restrictions, Lists and Unions (XSM)
You can use derivations to extend or restrict the values of elements and of simple and complex types.
Annotations (XSM)
Annotations allow you to add information about an XSD model. Annotations can be added at the schema level or on any element or other object within an XML model targeted with XSD.
Notations (XSM)
Notations allow you to define and process non-XML objects within an XML model.
Entities (XSM)
Entities enable you to include predefined values, external XML or non-XML files in an XML model targeted with a DTD.
Instructions: Import, Include and Redefine (XSM)
Import, Include and Redefine allow you to enrich your XML model with external namespaces, schema files or schema components.
Business Rules (XSM)
A business rule is a rule that your business follows. It is a written statement specifying what an information system must do or how it must be structured. It could be a government-imposed law, a customer requirement, or an internal guideline.